The invention relates to signal processing arrangements and particularly to arrangements for enhancing information signals with respect to interference.
In the electrical arts there exists a need for processing signals occurring in a background of noise or undesired signals. For example, in application Ser. No. 649,791 by Garold K. Jensen, filed concurrently herewith, there is disclosed a velocity and acceleration radar system designed to provide good doppler resolution for both constant-velocity and accelerating targets. That system detects accelerating targets by spectrally compressing the acceleration-spread doppler frequency spectrum, but the same frequency modulation that is employed to compress the spectrum of the return signal from an accelerating target produces frequency spreading of the signal energy from constant velocity targets. In such a case a large-amplitude signal from a constant velocity target will be detected and displayed over a wide band of doppler frequencies with nearly equal amplitudes so that an accurate doppler or velocity reading is not possible. Other smaller amplitude signals of interest may occur within the region of doppler spreading of the larger signal and these signals will then be masked by the larger spread signals.
Large-amplitude jamming signals are also spread in a similar manner and some arrangement is desirable to favor the information signals over the undesired jamming signals. Merely limiting the total incoming signal is not suitable because a very large signal can, in the limiting process, "capture" small signals existing anywhere in the whole information band. A more selective arrangement for discriminating against this interference is desired.